The entire disclosure of Japanese Patent Application No. 2002-238482 filed on Aug. 19, 2002 including the specification, claims, drawings and summary is incorporated herein by reference in its entirety.
1. Field of Invention
This invention relates to a junction box and more particularly it relates to a junction box that is connected to a wire harness for an automobile and firmly holds a fuse module in a side opening.
2. Description of Related Art
Recently, as electrical components installed on an automobile have suddenly increased, so has the number of circuits contained in a junction box. The number of parts to form branched circuits at a high density has also increased extremely. This increase requires many assembling steps.
For convenience of explanation, a prior art junction box will be described by referring to FIG. 7. FIG. 7 is an exploded perspective view of a conventional junction box 1.
The present applicant has proposed a junction box as shown in FIG. 7 in order to form a thin type junction box, to easily change a circuit design, and reduce assembling steps.
In junction box 1, a connector connecting circuit section (base circuit section), a fuse connecting section, and a relay connecting section are divided into a connector module 5, a fuse module 8, and a relay module 6. An ECU (electronic control unit) 3, an insulation board 4, a connector module 5, and a relay module 6 are stacked from an upper stage to a lower stage in order in a casing that includes an upper casing member 2 and a lower casing member 7.
An opening 2c is formed on a sidewall of the upper casing member 2. A fuse casing 9 of the fuse module 8 is attached to the opening 2c. Locking-portions 2b on opposite sidewalls 2a of the upper casing member 2 engage portions being locked 7a on opposite sidewalls of the lower casing member 7 and the fuse module 8 is attached to the upper and lower casing members 2 and 7.
In the case where the junction box is divided into the connector module, fuse module, relay module, and relay module, each are divided into the connector connecting circuit, fuse connecting circuit, and relay connecting circuit. Accordingly, tabs of bus bars are not overlapped. Consequently, it is possible to suppress a multi-lamination of the bus bars and to reduce a thickness of the junction box. Since an arrangement of a bus bar circuit becomes simple, it is possible to reduce an area of the bus bar. Even if the bus bar is divided, it is still possible to reduce a whole area of the bus bar and to suppress an increase of area of the junction box.
Furthermore, if there is an alteration in the specification, for example, in a connector circuit, a fuse circuit, or a relay circuit, only a corresponding module can be altered. This can comply with an alteration in specification and, thus, an alteration in the circuit.
However, since the opening 2c is formed on a side of a peripheral wall of the upper casing 2 of the junction box 1, opposing sidewalls of the opening 2c are likely to be opened outwardly. When the opposing sidewalls are opened outwardly, the locking-portions 2b of the upper casing member 2 and the portions being locked 7a of the lower casing member 7 are unlocked, and casing member 2 and lower casing member 7 are detached from one another.
In view of the above problems, an object of the present invention is to provide a junction box having a side opening in which an upper and lower casing members are firmly interlocked.
In order to overcome the above problems, the present invention is directed to a junction box that includes an upper casing member and a lower casing member with a side opening to which a fuse module is attached. The fuse module contains an insulation board on which a bus bar is secured. The bus bar is connected to terminals of each of a plurality of fuses mounted in a fuse casing in a juxtaposed manner. Fuse casing locking-portions project from an upper surface of the upper casing member and a lower surface of the lower casing member at the side opening. The portions being locked are provided in the fuse casing to engage with the locking-portions on the upper and lower casing members. Thus, the upper and lower casing members are interlocked through the fuse casing.
According to the above, the fuse casing locking-portions of the upper and lower casing members are secured to the portions being locked of the fuse casing that encloses the side opening. Since the fuse casing serves as an interlocking means between the upper and lower casing members, it is possible to prevent the upper casing member from being separated away from the lower casing member, even when the opposing sidewalls of the side opening are opened outwardly.
Moreover, a fuse cover is mounted on an exterior of the fuse casing to further secure the upper casing with the lower casing. The portions being locked are provided on a peripheral wall of the fuse cover. The fuse casing locking-portions that project from the upper and lower casing members are provided on distal ends with cover locking-portions. The cover locking-portions engage the portions being locked of the fuse cover.
Furthermore, according to the above construction, the upper and lower casing members are provided on the positions opposed to the side opening with cover locking-portions while the fuse cover is provided with portions being locked. When the fuse cover is mounted on the fuse module with the fuse being contained in the fuse casing, the upper and lower casing members can be interlocked.
Thus, the upper and lower casing members are interlocked by both fuse casing and fuse cover. Such a double locking can secure the upper and lower casing members to each other more firmly.
In more detail, locking holes are provided on a stepped portion projecting from each of the upper and lower surfaces of the fuse casing so that the locking holes serve as the portion being locked. Arms that project into the side opening are provided on upper and lower surfaces of the upper and lower casing members respectively. The upper and lower surfaces are attached to the fuse casing vertically. Locking pawls for the fuse casing locking-portions are provided on the arms, so that the locking pawls are inserted into the locking holes in the fuse casing. A locking pawl is also provided on a distal end of each of the upper and lower surfaces of the upper and lower casing members so that the locking pawl serves as the cover locking-portion. The locking pawls of the cover locking portions also lock onto the periphery of the fuse cover.
Also, a connector module constituting a connector connecting circuit section is contained in an interior of a box within the upper and lower casing members. A relay module constituting a relay connecting circuit section is also attached to an opening in the upper or lower casing member. The connector module includes an insulation board and a bus bar secured to the insulation board whereas the relay module includes an insulation board and a bus bar that is connected to terminals of each relay.
The bus bar disposed vertically in the fuse module is coupled to the bus bar disposed vertically in the connector module by a resistance welding to arrange the fuse module on a side surface with the connector module. Under this condition, when the upper and lower casing members cover the fuse casing in upper and lower directions, the arms of the upper and lower casing members are deflected and the locking pawls on the arms engage the locking holes in the fuse casing. Thereby improving workability.
Still other objects and advantages of the invention will in part be obvious and apparent from the specification.